Merge pull request #304 from libigl/cubic-bezier-and-roots

Add bindings + tests for cubic Bézier, roots, and new predicates

Author: alecjacobson

.gitignore

@@ -5,6 +5,7 @@ external
 bin
 bin_rel
 build
+build-full
 
 tutorial/data
 tutorial/.ipynb_*

CMakeLists.txt

@@ -36,6 +36,18 @@ FetchContent_Declare(
 )
 FetchContent_MakeAvailable(nanobind)
 
+# Pin Eigen to 3.4.0. Recent libigl bumped its Eigen dependency to 5.0.1, whose
+# stricter ScalarBinaryOpTraits rejects the int64-vs-int comparisons in some
+# libigl headers (e.g. unique_edge_map), which the 64-bit-index Python bindings
+# instantiate. Declaring Eigen first makes FetchContent use this version instead
+# of the one requested by libigl's own recipe.
+FetchContent_Declare(
+  eigen
+  GIT_REPOSITORY https://gitlab.com/libeigen/eigen.git
+  GIT_TAG        tags/3.4.0
+  GIT_SHALLOW    TRUE
+)
+
 # Download and set up libigl
 option(LIBIGL_COPYLEFT_CORE        "Build target igl_copyleft::core"       ON)
 option(LIBIGL_COPYLEFT_CGAL        "Build target igl_copyleft::cgal"       ON)
@@ -44,10 +56,11 @@ option(LIBIGL_COPYLEFT_TETGEN      "Build target igl_copyleft::tetgen"     ON)
 option(LIBIGL_RESTRICTED_TRIANGLE  "Build target igl_restricted::triangle" ON)
 option(LIBIGL_SPECTRA              "Build igl::spectra bindings"           ON)
 option(LIBIGL_PREDICATES           "Build igl::predicates bindings"        ON)
+option(LIBIGL_CYCODEBASE           "Build igl::cycodebase bindings"        ON)
 FetchContent_Declare(
   libigl
   GIT_REPOSITORY https://github.com/libigl/libigl.git
-  GIT_TAG 678e1fff76815e0c4c5d1f025ee2129181cc7d86
+  GIT_TAG 477e15a3d566a21f415aa5ee62992b12a836b01b
 )
 FetchContent_MakeAvailable(libigl)
 
@@ -190,6 +203,9 @@ endif()
 if(LIBIGL_PREDICATES)
   pyigl_include("" "predicates")
 endif()
+if(LIBIGL_CYCODEBASE)
+  pyigl_include("" "cycodebase")
+endif()
 
 
 

pyproject.toml

@@ -13,7 +13,7 @@ build-backend = "scikit_build_core.build"
 
 [project]
 name = "libigl"
-version = "2.6.3.dev3"
+version = "2.6.3.dev4"
 description = "libigl: A simple C++ geometry processing library"
 readme = "README.md"
 requires-python = ">=3.8"

src/cubic.cpp

@@ -0,0 +1,29 @@
+#include "default_types.h"
+#include <igl/cubic.h>
+#include <nanobind/nanobind.h>
+#include <nanobind/eigen/dense.h>
+
+namespace nb = nanobind;
+using namespace nb::literals;
+
+namespace pyigl
+{
+  auto cubic(
+    const nb::DRef<const Eigen::MatrixXN> &C,
+    const Numeric t)
+  {
+    Eigen::MatrixXN P;
+    igl::cubic(C, t, P);
+    return P;
+  }
+}
+
+void bind_cubic(nb::module_ &m)
+{
+  m.def("cubic", &pyigl::cubic, "C"_a, "t"_a,
+    R"(Evaluate a cubic Bézier curve defined by control points C at parameter t.
+
+@param[in] C  4 by dim matrix of control points for a cubic Bézier curve
+@param[in] t  parameter at which to evaluate the curve
+@return P  1 by dim point on the curve C(t))");
+}

src/cubic_is_flat.cpp

@@ -0,0 +1,31 @@
+#include "default_types.h"
+#include <igl/cubic_is_flat.h>
+#include <nanobind/nanobind.h>
+#include <nanobind/eigen/dense.h>
+
+namespace nb = nanobind;
+using namespace nb::literals;
+
+namespace pyigl
+{
+  bool cubic_is_flat(
+    const nb::DRef<const Eigen::MatrixXN> &C,
+    const Numeric squared_distance_bound)
+  {
+    return igl::cubic_is_flat(C, squared_distance_bound);
+  }
+}
+
+void bind_cubic_is_flat(nb::module_ &m)
+{
+  m.def("cubic_is_flat", &pyigl::cubic_is_flat, "C"_a, "squared_distance_bound"_a,
+    R"(Test whether a cubic Bézier curve is flat within a given tolerance.
+
+"Piecewise Linear Approximation of Bézier Curves" [Fischer 2000]. If the test
+passes, the curve's maximum squared distance to the chord from its first to its
+last control point is less than squared_distance_bound.
+
+@param[in] C  4 by dim matrix of control points for a cubic Bézier curve
+@param[in] squared_distance_bound  squared distance tolerance
+@return True if the curve is flat within the given tolerance)");
+}

src/cubic_monomial_bases.cpp

@@ -0,0 +1,35 @@
+#include "default_types.h"
+#include <igl/cubic_monomial_bases.h>
+#include <nanobind/nanobind.h>
+#include <nanobind/eigen/dense.h>
+#include <nanobind/stl/tuple.h>
+#include <tuple>
+
+namespace nb = nanobind;
+using namespace nb::literals;
+
+namespace pyigl
+{
+  auto cubic_monomial_bases(
+    const nb::DRef<const Eigen::MatrixXN> &C)
+  {
+    Eigen::MatrixXN M, D;
+    // B is a 6-vector of inner products (cubic_monomial_bases calls vector
+    // methods on it), so it must be a vector type, not a general matrix.
+    Eigen::VectorXN B;
+    igl::cubic_monomial_bases(C, M, D, B);
+    return std::make_tuple(M, D, B);
+  }
+}
+
+void bind_cubic_monomial_bases(nb::module_ &m)
+{
+  m.def("cubic_monomial_bases", &pyigl::cubic_monomial_bases, "C"_a,
+    R"(Compute monomial basis representations for a cubic Bézier curve.
+
+@param[in] C  4 by dim matrix of control points for a cubic Bézier curve
+@return Tuple (M, D, B) where
+  M  4 by dim matrix of monomial coefficients for C(t)
+  D  3 by dim matrix of monomial coefficients for dC/dt
+  B  6-vector of inner products of those basis functions for C(t))");
+}

src/cubic_split.cpp

@@ -0,0 +1,33 @@
+#include "default_types.h"
+#include <igl/cubic_split.h>
+#include <nanobind/nanobind.h>
+#include <nanobind/eigen/dense.h>
+#include <nanobind/stl/tuple.h>
+#include <tuple>
+
+namespace nb = nanobind;
+using namespace nb::literals;
+
+namespace pyigl
+{
+  auto cubic_split(
+    const nb::DRef<const Eigen::MatrixXN> &C,
+    const Numeric t)
+  {
+    Eigen::MatrixXN C1, C2;
+    igl::cubic_split(C, t, C1, C2);
+    return std::make_tuple(C1, C2);
+  }
+}
+
+void bind_cubic_split(nb::module_ &m)
+{
+  m.def("cubic_split", &pyigl::cubic_split, "C"_a, "t"_a,
+    R"(Split a cubic Bézier curve at parameter t into two cubic Bézier curves.
+
+@param[in] C  4 by dim matrix of control points for a cubic Bézier curve
+@param[in] t  parameter at which to split the curve
+@return Tuple (C1, C2) where
+  C1  4 by dim control points of the sub-curve from C(0) to C(t)
+  C2  4 by dim control points of the sub-curve from C(t) to C(1))");
+}

src/cycodebase/box_cubic.cpp

@@ -0,0 +1,50 @@
+#include "default_types.h"
+#include <igl/cycodebase/box_cubic.h>
+#include <nanobind/nanobind.h>
+#include <nanobind/eigen/dense.h>
+#include <nanobind/stl/tuple.h>
+#include <tuple>
+
+namespace nb = nanobind;
+using namespace nb::literals;
+
+namespace pyigl
+{
+  // Bounding box of a single cubic Bézier curve.
+  auto box_cubic_C(
+    const nb::DRef<const Eigen::MatrixXN> &C)
+  {
+    Eigen::RowVectorXN B1, B2;
+    igl::cycodebase::box_cubic(C, B1, B2);
+    return std::make_tuple(B1, B2);
+  }
+  // Bounding boxes of many indexed cubic Bézier curves.
+  auto box_cubic_PC(
+    const nb::DRef<const Eigen::MatrixXN> &P,
+    const nb::DRef<const Eigen::MatrixXI> &C)
+  {
+    Eigen::MatrixXN B1, B2;
+    igl::cycodebase::box_cubic(P, C, B1, B2);
+    return std::make_tuple(B1, B2);
+  }
+}
+
+void bind_box_cubic(nb::module_ &m)
+{
+  m.def("box_cubic", &pyigl::box_cubic_C, "C"_a,
+    R"(Compute the min/max box corners tightly containing a cubic Bézier curve.
+
+@param[in] C  4 by dim matrix of control points defining the cubic Bézier curve
+@return Tuple (B1, B2) where
+  B1  1 by dim min corner of the bounding box
+  B2  1 by dim max corner of the bounding box)");
+
+  m.def("box_cubic", &pyigl::box_cubic_PC, "P"_a, "C"_a,
+    R"(Compute bounding boxes for a collection of indexed cubic Bézier curves.
+
+@param[in] P  #P by dim matrix of control point locations
+@param[in] C  #C by 4 matrix of indices into P defining the cubics
+@return Tuple (B1, B2) where
+  B1  #C by dim matrix of min corners of the bounding boxes
+  B2  #C by dim matrix of max corners of the bounding boxes)");
+}

src/cycodebase/module.cpp

@@ -0,0 +1,11 @@
+#include <nanobind/nanobind.h>
+namespace nb = nanobind;
+
+// generated by cmake
+#include "cycodebase/BINDING_DECLARATIONS.in"
+
+NB_MODULE(pyigl_cycodebase, m) {
+  m.doc() = "libigl cycodebase module python bindings";
+  // generated by cmake
+#include "cycodebase/BINDING_INVOCATIONS.in"
+}

src/cycodebase/point_cubic_squared_distance.cpp

@@ -0,0 +1,36 @@
+#include "default_types.h"
+#include <igl/cycodebase/point_cubic_squared_distance.h>
+#include <nanobind/nanobind.h>
+#include <nanobind/eigen/dense.h>
+#include <nanobind/stl/tuple.h>
+#include <tuple>
+
+namespace nb = nanobind;
+using namespace nb::literals;
+
+namespace pyigl
+{
+  auto point_cubic_squared_distance(
+    const nb::DRef<const Eigen::MatrixXN> &Q,
+    const nb::DRef<const Eigen::MatrixXN> &C)
+  {
+    Eigen::VectorXN sqrD, S;
+    Eigen::MatrixXN K;
+    igl::cycodebase::point_cubic_squared_distance(Q, C, sqrD, S, K);
+    return std::make_tuple(sqrD, S, K);
+  }
+}
+
+void bind_point_cubic_squared_distance(nb::module_ &m)
+{
+  m.def("point_cubic_squared_distance", &pyigl::point_cubic_squared_distance,
+    "Q"_a, "C"_a,
+    R"(Squared distance from each query point to a cubic Bézier curve.
+
+@param[in] Q  #Q by dim matrix of query points
+@param[in] C  4 by dim matrix of control points for the cubic Bézier curve
+@return Tuple (sqrD, S, K) where
+  sqrD  #Q vector of smallest squared distances
+  S     #Q vector of parameters of the closest points on the curve
+  K     #Q by dim matrix of closest points on the curve)");
+}